Notes on Critical Velocity

This work is in progress. I realised I was just keeping it as such forever as
my will to continue it comes and goes. I decided to just put it on the
internet, though without being readily linked. If you get to this page,
beware.

Critical velocity (CV for short) in running is defined by Tom ‘Tinman’ Schwartz
(Citation needed. He does seem to have popularised it at least). It is a pace
you can race for 30 minutes. Tinman calls it “somewhat hard”. Comparing it to
some Jack Daniels paces, it would be faster than Threshold (hour race
pace), but slower than Intervals (~VO2max, 11ish minutes race pace). See it
as yet another pace you can decide to train at. Tinman says it is helpful from
800m to definitely 10 km, though he suspects it helps all the way to the
marathon.

What Does It Improve

Improves aerobic capacity of Type IIA muscle fibers. These fibers can be
specialised to be more aerobic or more anaerobic, depending on what training
you throw at them. CV makes them “consumers of oxygen and producers of power”.
Helps with sustaining pace for 800m and more races. Tinman argues it helps all
the way up to marathons.

The muscle improvements lead to the following two noticeable effects. First, it
elevates the average cruising speed during races. This means you can stay
cruising for a longer time without increasing fatigue. Second, it improves your
kick. Specifically, it improves from how far from the finish line you can start
your kick, i.e., the length you can sustain the kick.

Finding Your CV Pace

You could go out for a fully rested 30 minute race effort, but that is probably
harder to plan in. You likely have somewhat of an idea of the range to go for,
but if you want more precise numbers, Tinman provides an online
calculator. Just enter any recent or representative race
time. Others12 have suggested doing a 3 minute all out run.
That is, after a sufficient warmup, you start running all out from the start.
You just keep going as hard as you can for 3 minutes. Your pace will flatten
out somewhat eventually. The pace in the last 30 seconds is your critical
velocity. This last method is useful if you do not have race efforts to go by.

You could also try by feel, of course, though that may prove much trickier. As
mentioned in the intro, Tinman describes CV pace as ‘somewhat hard’. I have
also heard it described as being right between comfortably hard (a description
often attributed to the 1 hour race pace, T pace in Daniels speak) and on
the edge. In that context a VO2max workout (I pace, ~11 minute race pace)
feels like “a little to a lot under the edge”.3

How to Train at CV Pace

The eventual goal seems to be repetitions of around 2 to 5 minutes with
recovery lasting about one third of the repetition’s duration. The maximum
total duration at CV pace would be around 25 minutes (as mentioned in a video
of tinman). From what I have heard, us average runners may be happier at 20
minutes maximum. Another more precise number I have heard, but one for which I
did not look for a proper source, is dividing 420 by your 5 km time in minutes.
This gives you maximum time at CV, also in minutes.

Getting to this eventual point may take you several sessions though. Start out
with longer recoveries or shorter repetitions. Post workout recovery is about
2-3 days. Add a few extra recovery days in case a race follows.

You can do CV workouts year round. There is no specific CV phase in your
build-up. Limit yourself to one a week or one every other week.

An Example

As an example, planning and analysing my first CV session went as follows. To
make up a workout, I just picked a duration on the lower end of the 2 to 5
minutes range, considered my CV pace, and picked a distance that fit with
things. In my case, Tinman’s calculator put my 800m time in
a CV training at the 2:5x neighbourhood. Under 3 minutes seems like a safe
place to start. Finding a distance to aim at will make it easier to do this
correctly on a track. I like the precision versus GPS. I started with just 4
reps, and used a recovery of ~1:30 rather than the ~1:00 you would expect in
the ideal situation (i.e., a third of just shy of 3 minutes). In my case, this
workout felt a bit too easy, though of course a first workout is to get used to
things. Your mileage may vary.

How to improve from here to the theoretical maximum is pretty obvious, there
are not a whole lot of variables to play with. Either increase the repetitions,
increase the repetition duration, or decrease the rest. In all three cases, you
evidently do not want to cross the maxima mentioned above (maximum 25 minutes
total, maximum 5 minutes per rep, minimum a third of duration recovery). I will
likely bump my next CV workout up to 6×800 next time with a little shorter
rest.

As always, if it takes you too long to recover in the days following a workout,
then you probably overdid it.

More

TODO: I had some sources dumped into my onedrive. Ensure their information is
incorporated.

Letsrun has (at least) two articles about/with Tinman and CV. Though I
believe they were the more boring muscle talk.

There are some scientific papers

Further Reading

I did not come up with anything in this blog post, I am combining information
from various other sources. Give them a read to ensure I correctly distilled
information.